


After School Activities

by DeliveryHomo



Category: Assassination Classroom
Genre: Established Relationship, Hand Jobs, M/M, Mutual Masturbation, Top!Nagisa is best Nagisa
Language: English
Status: Completed
Published: 2015-06-13
Updated: 2015-06-13
Packaged: 2018-04-04 06:59:07
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,072
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4129014
Author URL: https://archiveofourown.org/users/DeliveryHomo/pseuds/DeliveryHomo
Summary: <blockquote class="userstuff">
              <p>Karma and Nagisa sneak out after school, having the wooden classroom all by themselves.</p>
            </blockquote>





	After School Activities

The old, wooden building of Class E wasn't exactly the best place to hang around after class. Usually, once the school hours had ended, everyone just walked back home after one or two failed assassination attempts. After all, it took some of the students up to two hours to go back home after walking down that isolated hill, and really there wasn't much for them to do up there once Korosensei flew to Spain to watch a football match.

Today, however, the door of the classroom had been purposely left open by the student who was supposed to close it after class. Two boys walked into the room, their footsteps and nervous giggling the only sound in the building.

“Ahh, we're really doing this!”

“Karma-kun!” Nagisa turned around as soon as the red-haired boy closed the door behind them. His eyes were gleaming with excitement, his lips curling up in a playful smile. It was the things like this – sneaking around, picking up fights, stealing small things – that made Karma's eyes take that look.

Nagisa, on the other hand... He was just plain nervous.

“What? You were the one who unlocked it for us.” Karma replied, sticking out his tongue like he always did when he was confident. He probably meant it to be irritating, but Nagisa couldn't help but find it kind of cute.

Ignoring his complains, Karma started moving away from the door. He looked around, his hands resting in his pocket, and the smaller boy just followed him.

“It feels strange... I mean, it being so quiet.” Karma, who had been touching a wooden desk, looked at him once Nagisa opened his mouth. “Usually everyone gets around here to talk about every kind of things... it's a bit lonely.”

“Hmm...” The red-haird boy hummed, the smile on his lips widening. “Well, I think I can understand that.” A few footsteps were heard as he walked toward the smaller one, yellow eyes fixed on his. “I have to admit, it's kinda fun talking with everyone. And it's because of this classroom that we're together now, so guess I should be thankful.”

“Karma-kun...” In the time it took Nagisa to call out his name, Karma walked the remaining distance between them. His hands slid at his sides, holding him by the lower part of his back, their chest almost touching. It was exciting, being like this in the empty classroom where they'd never done as much as holding hands. He could understand now why Karma had suggested to sneak out together, and was starting to wish he'd agreed so much sooner.

“Nagisa-kun.” The words left his lips in a whisper, as if there was any need of privacy in the empty classroom. He had that look in his eyes, the look Nagisa couldn't help but notice was only ever given to him. The kind of look that made his cheeks blush and feel butterflies in his stomach.

There was no need for any more words, no when they could feel each others' heart beat with expectation against their chests. Instead, Karma ducked his head until his lips founds Nagisa's, holding him closer. Although it started slow and almost caste, it didn't take long until Nagisa put his arms around Karma's neck. Kissing him deeper, having Karma kiss him back almost needy.

It had been a surprise, Karma had to admit, the first time Nagisa had shown that side of him while being the two of them alone. He never expected him to be the one to start the deepest kiss, or the one to playfully start biting his mouth. But he didn't dislike it, not the slightest.

Karma's hands moved slowly, enjoying every centimeter, until he reached Nagisa's tights. The contact made the smallest boy whimper between their lips, a precious sound that only made him want to hear again and again.

However, Nagisa parted their kiss. Karma looked at him, lips still open and eyes slightly furrowed. He couldn't stop now. He didn't want to. After all they'd finally managed to sneak out, it would be a waste if they just backed off now.

Nagisa's cheeks were red, and his breath uneven when he spoke. “Not here...” He whispered. Karma opened his mouth to protest, but he was faster. “This is Isogai's desk... we should do this in yours.”

Ah. Now that he mentioned it, that made sense. God knew what they would end up doing, and messing up another student's desk would be a bad idea. So he let go of Nagisa, stepping back just enough for him to start walking towards the back row of desks where Karma usually sat.

The red-haired boy followed him, both of their uneven breaths mixing in the air. Once they reached his desk, however, Karma stopped.

“...Do you think she can hear us?”

Nagisa blinked, slightly confused, until he followed Karma's gaze.

There, standing just like always, was Ritsu. Or at least, her hardware.

“Ah...” The sudden realization of her having seen them just now made Nagisa's cheeks flush. He hurriedly took his phone out of his pocket and turned it off, just in case. Meanwhile, Karma had walked towards Ritsu and was now looking around the computer.

“Hey~ Ritsu~ Are you there?” Karma knocked the screen a few times, but no answer came out. So he looked back at Nagisa, shrugging. “Maybe she's in sleep mode?”

“That doesn't sound too reassuring, Karma-kun...”

“It's fine! I don't think she'll be able to see us from there, anyways.” Karma walked towards him once again, until they were both in his desk.

“That doesn't mean she wouldn't be able to hear us...” Nagisa mustered, which made Karma smile.

“Then I suppose we better not be too noisy?”

He smiled softly, reaching out to take Karma's collar and tugging him until their faces were close again. “I should be the one saying that.”

Karma smiled back at him, and right before he knew it, they were kissing again. Deeply, needy, as if they hadn't been doing this just a minute ago.

This time, Karma managed to put his hands under Nagisa's tights, and pulled him over so he could sit in his desk. Once the height difference was out of the way, it became easier to kiss more deeply even than before, hands buried inside of each other's hair.

Once again, Nagisa parted their kiss. This time, however, he moved his mouth to place small kisses all over Karma's jawline, until he reached his neck. Karma's hands had ended in Nagisa's shoulders at some point, and only held him more tightly when the kisses became louder against the skin of his neck.

“That's going to leave a mark...” Karma breathed heavily, and he could feel Nagisa smile against his skin. Although he didn't say it out loud, he could almost hear him say “That's what I wanted.”

However, just because Nagisa was the one taking the lead right now it didn't mean he should slack off. Undressing each other was probably out of the question – even if they were alone, it just didn't feel right to get naked in their classroom, but there were no rules on what he could do as long as their clothes were still where they were supposed to be.

So he moved his hands down Nagisa's chest, the contact making the smaller one sigh as he kept kissing his skin. He didn't stop until he reached the bottom of his vest, and slid them under his clothes. His skin was soft and warm, and he reacted to the contact with yet another sigh.

“Karma-kun...” He whispered. In the time it took Karma to reach the skin of the lower part of Nagisa's chest, he had managed reach his clavicle with his kisses, his hands holding him closer by the back.

It felt good. Nagisa's tongue against his skin, his hands gripping his black cardigan. The fact that they were doing this in their classroom, a place not meant for such acts. The soft tact of Nagisa's skin, and-

He left out a sigh when he felt the pressure against his crotch. Looking at him, Nagisa's lips drew a proud smile. “Isn't it a bit early? We haven't even started yet.”

Karma couldn't help but swallow dry, expectation building up with every second he help Nagisa's gaze. He didn't waste a single second and started moving his knee. Slowly, painfully so, as Karma sighed again.

It was a cheesy thing to say, and he knew it didn't fit his character, but he loved the fact that there was a part of Nagisa only he knew. The part that enjoyed teasing him like, that. The part that looked at him with those eyes, knowing fully well how to act in order to get a reaction out of him. The part that made him beg for more under his breath.

There was no one else in the world who'd ever seen that part of Nagisa. And that made him feel even better every time.

“You're so cruel, Nagisa-kun...” He whispered, shutting his lips just in time to conceal a small moan.

Nagisa just smiled, now making a bit more of pressure against Karma's crotch.

He knew what was coming. Nagisa would continue to tease him, and he wouldn't be satisfied until he had him moaning and begging him to please just let him come.

And as much as he loved that kind of dynamic, he couldn't let him win every time. So he hurriedly joined their lips again, kissing deeply once again in order to suppress the sounds coming out of his mouth between their lips.

If Nagisa wasn't wasting any time, he thought, he wasn't going to waste time either. He took out of Nagisa's clothes and started undoing his belt. Hands shaking and thoughts blurred thanks to the blue haired's movements, it took a bit of trial and error until he parted the kiss just long enough to see what he was doing and finally get the stupid belt out of the way.

Once that was dealt with, it didn't take him so long to undo his pant's button and unzip them, until he had enough room to feel Nagisa over his underwear.

Fully aware of Karma's movements, Nagisa ditched the circular movements of his knee to start moving it back and forth, increasing the pressure. The feeling made him moan loudly once again, muffled between their kiss.

When Karma pulled out, both of them were breathing heavily, unevenly. Karma had started massaging Nagisa's erection over his underwear, as they locked gazes. Even now, Nagisa looked like he was the one in charge. Like he knew exactly what he should do, what buttons to press to make Karma react one way or the other. And to be honest, he probably did.

That's why Karma knew that the only thing that worked under these circumstances was to do as he wanted. “Nagisa-kun... touch me...”

His voice came out needy, more than he intended. But he had no time to feel ashamed, not when Nagisa obediently did as he asked and moved his leg out of the way, just to start undoing Karma's belt.

He had to admit, Nagisa was way more skilled at undoing belts and unziping pants than he was. In half the time it took Karma to just get the belt done, Nagisa's hand was already teasing against Karma's underwear, his pants slightly pulled down so he could reach better.

A low groan left Karma's lips when he felt Nagisa's slender fingers, slowly moving along his shaft. He cursed his underwear for being in way, when he just wanted to have Nagisa touching him more, and more, and more.

He wished he could be more like him in this kind of situation. He wished he could keep his cool as long as him, tease him back and keep this game up. But he wasn't like Nagisa. He needed the contact, needed Nagisa touching him and to touch Nagisa. And although he knew no one would be coming at this time, when the sun was starting to set and the classroom started to become dark, it felt as if the place was urging them to do it fast.

So he didn't waste time and hurriedly tugged down Nagisa's underwear, revealing his erected cock. The smaller boy moaned next to his ear, and that was enough reward. He used the tip of his fingers to outline his length, until he finally wrapped his hand around him and started moving it.

He felt Nagisa's small, thin body shake under him. His head hidden against Karma's neck, the moans against his skin told him Nagisa had been wanting this as much as he had.

Before long, both of them were in the same position. Underwear tugged down, almost falling out of Karma's hips, and the other boy's hands around it. Their rythms were uneven and mismatched, and they both knew they could do so much better than that. However, with Nagisa sitting on the desk Karma used every day in class, doing it imperfectly felt so good, so fitting...

He could feel his legs shaking, and at this rate he knew it wouldn't take him too long. But not yet, not just yet, he thought. He moved his free hand in Nagisa's back, using it to draw him closer. He heard his feet touching the ground under their uneven breaths and casual moans, and now that they were close enough, Nagisa seemed to understand what Karma was trying to achieve.

So he left Karma take the lead for once, as the red-haired opened his hand and tried to catch both of their cocks with it. It was a strange feeling, but it wasn't unpleasant at all having Nagisa's dick touching him. Once his hand was ready, Nagisa joined. This time together, with a better rhythm, their movement started again.

It felt hot, and it felt so good. His skin touching Nagisa's, the warmth of Nagisa's hand, and... when did he start moaning so loud? It was him who'd said they should be quiet in case Ritsu had some time of sound alarm, yet he had been the first one to give him. At least Nagisa was doing the same, calling out his name between sharp breaths, and god just hearing him made him feel pleasure.

“Nagi-” Inevitably, he was the first one to come, hand gripping harder against their cocks and he hit orgasm. His body shook and his legs felt weak after standing up for so long, but he kept on until Nagisa's legs wrapped his hips and he felt the hot substance on his hand.

It took them a moment to part, trying to catch their breaths. Nagisa's cheeks and ears were red, but the hot feeling on his head told him he probably was the same color as his hair right now.

“Ah...” Nagisa opened his mouth, looking down at their hands. “Wait a moment, I have some tissues here...”

Karma stepped back, leaving Nagisa with enough space to reach to his back pocket and take out a small box of tissues. He handed one to Karma and used the other one to wipe his own hand and penis.

“Say, Karma-kun...” He said once he was done with that. “Didn't you say we shouldn't be loud?”

He knew it. Even though Nagisa had been just as loud as him, he didn't hesitate to bring that up.

“Ah, but that was only because of Ritsu. She's probably asleep or in someone's phone, I doubt she's heard anything.”

Karma turned his head to look back at the big, black block of Ritsu's hardware. He couldn't believe he hadn't thought of her when suggesting Nagisa to sneak out into the classroom together, especially considering something as big as her wasn't really that easy to ignore.

When he looked back at Nagisa, he found him staring at him with a tender smile. He smiled back, leaning down to kiss him just for a small moment, and then looked at the classroom's windows. Outside, the sun had already set almost completely, turning the trees into a dark cloud they'd have to walk through in order to go back home safely.

“Well then, I guess we should get going.”

Nagisa stood up and finished fixing himself up after standing on his tiptoes and kissing Karma again, a repetition of their previous kiss. “Yeah.”

A smile, wider than he could control, appeared on his face after that kiss. He felt like holding Nagisa's hand as they started walking towards the back door, but first they should probably get rid of their used tissues.

...However.

“Not that fast!”

The sound of something moving much faster than a bullet right behind them made the two boys stop frozen in place, a cold sweat running down their backs.

“Seriously...?”

He wished he was wrong. He really did. But when they turned their heads to look what was behind them... they found him.

His never changing wide smile, those small eyes (or was that his nose?) and the yellow tentacles touching each of their shoulders.

“Nagisa-kun, Karma-kun. What's the meaning of this?”

“K-Korosensei... We were just... ah...” Karma and Nagisa looked at each other, both seeking for help. And both unable to come up with any excuse.

 _It's okay. Maybe he's only talking about being here so late._  That's what Nagisa was hoping, at least.

“I know you're in that age, but I ask you to not do this kind of thing in the classroom. This is a place for education!”

_M-Maybe he's talking about the kiss..._

“And more importantly!”

In less than a second, Karma and Nagisa found themselves sitting in the first row of seats. They looked at each other in the confusion of being dragged by a tentacle monster at Mach 20, and before they had enough time to say anything, a pamphlet had appeared on top of each of their desks.

The pamphlet read “Safe Sex For Everyone: Boy's Love Edition”.

Handmade by Korosensei.

“Since you two seem to be pretty active, I can't have you doing things like this without having properly explained the importance of safe sex.”

Nagisa's face was burning red with embarrassment. And if he hadn't been too ashamed to even look at their teacher, Karma would have jumped and attacked him until he had shut up about condoms, and lube, and safe words.

 

**Author's Note:**

> Reposting from my tumblr! This is my first time writing Karma/Nagisa but I'm sure it won't be the last. I saw flammable-fangirl request "a fic where Korosensei finds Karma and Nagisa fooling around" and just kinda went with it-


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